U.S. Constitution - Article 2 Section 2

The President shall be Commander in Chief of the Army and
Navy of the United States, and of the Militia of the several States, when
called into the actual Service of the United States; he may require the
Opinion, in writing, of the principal Officer in each of the executive
Departments, upon any subject relating to the Duties of their respective
Offices, and he shall have Power to Grant Reprieves and Pardons for Offenses
against the United States, except in Cases of Impeachment.

He shall have Power, by and with the Advice and Consent of
the Senate, to make Treaties, provided two thirds of the Senators present concur; and he shall nominate, and by and with
the Advice and Consent of the Senate, shall appoint Ambassadors, other public
Ministers and Consuls, Judges of the supreme Court, and all other Officers of
the United States, whose Appointments are not herein otherwise provided for,
and which shall be established by Law: but the Congress may by Law vest the
Appointment of such inferior Officers, as they think proper, in the President
alone, in the Courts of Law, or in the Heads of Departments.